Heat exchanger



May 27, 1941. J. P. ZALLEA HEAT EXCHANGER Filed Aug. 12, 1938 2 Sheets-Shegt l lNVENTOE JAMES F. ZALLEA f ATTORNEY May 27, 1941. J. P. ZALLEA HEAT EXCHANGER Filed Aug. 12, 1938- 2 Sheets-Sheet 2- v INYEHTOR'. JAMES R ZALLEA y f PM in, 21,1941

UNITED STATES PATENT OFFICE assesses unaraxacnsnosa 'lalneslfilalleatl'hihdelphlah. ApplicafleaAllsItu.10u.8eslalNa.224,451

. fluid 'through'the-wall or walls of the conduit which. separate the fluid to be'heated from the heatingmedium. Thistypeofapparatusisgeneraliytermedasheatexchan'gerandisespecially adapted forpreheating fluids, such as oil, by

theuseofaheatingmedium,suchassteam.

Among the principal obiects of the present invention is to provide a heat exchanger of high efllciency andin which a rapid transference of heatfromtheheatingmediumtothefluidtobe heated is effectively secured.

A further object is to provide a heat exchanger 'ofthetype eferredtowhichisnotonlyrelatively simple and inexpensive .to construct and assemble but which is also easy and economical to maintain and operate in service. the several parts ofthe apparatus being readily adapted for l'y whenever required for the purpose of making repairs or for cleaning without necessitating a complete disorganization of the entire ppm ult Heretofore and prior to the present invention heat exchangers have been employed in which concentric tubes" were employed, the heating fluid being delivered through one of these tubes in such manner that the heat thereof was transferred by conduction throush the wall thereof to the fluid passing through the other of said tubes. During the passage of the heating fluid through its conduit, it naturally loses more and more of its s Claims. (01. saw-s41 notonlyincreasetheheatingsurfaceareabut also insure an increased conductivityofthe flnnedconduitsoastofacilitateahighlyeifl- -cient and rapid transfer of heat between the heating medium conveyed within the-flnned conduitandthefluidtobeheatedasitisdelivered through tubing arranged concentrically about 1 said flnned conduit.

Other objects and advantages of the invention will be apparent more fully hereinafter, it being understood that the invention consists substantially in the combination, construction, location and relative arrangement of parts, all as described more fully hereinafter, as is shown in the accompanying drawings and as finally pointed out in th appended claims.

In the accompanying drawings:

Figure 1 is an eievational view of the apparatus constructed in accordance with and embodying the principles of the present invention. a portion thereof being shown in section to illustrate details of construction Figure 2 is a vertical sectional view of the apparatus taken on the line 2-2 of Figure 1; .-Figure 3 is a horizontal sectional view on an enlarged scale takenalong the line 3-3 of Figure 2;

Figure 4 is an elevational view of a somewhat modifled construction of the. apparatus;

Figure 51s a front elevational view of the front cover plate of the apparatus;

heat in consequence of which such heat exchangare very definitely have a lower rate of heat exqh l nlemciencyinthedischar'geordelivery side thereof than in the inlet side thereof. It is among the objects-of the present invention to provide a heat exchanger wherein the fluid to beheatedissubjectedtosubstantially thesame degree of heating temperature throughout its passage through the apparatus, thereby insuring a higher heat exchanging eillciency in the,

discharge d of apparatus than has been possible of attainment heretofore.

..Inadditiontotheforegoing,itisamongthe objects of this invention to increase the heat aschanging eiiiciency of the apparatus by providing the conduits for the heating medium with radially'proiecting fins of such character and Figure 6 is an enlarged elevational view or the outer end of the heating fluid flnned conduit assembly; and

ticularly to Figures 1 to 3 thereof which illustrate one form of the'apparatus constructed in accordance with and embodying the principles of the present invention, it will be observed that the apparatus comprises a multiple unit heat exchanger consisting of a plurality of units II, II, and it of similar construction and arranged substantially in vertically spaced relation. Each of these units includes a U-shaped tube ll, the open ends II and ll of which proiectthmughandaresecuredinanysuitable manner within a vertically disposed supporting plate II, the said U-ahaped tubes being further supported in the flxed relation shown by means of one or more supporting elements ll-il. Preferably,inordertoobtainascompactarelaas possible between the several units ticnship securedtotheconduitinsuchmannerthsttheyu llto is oftheapparatus, the U-shapedtubes l4 thereof are respectively disposed in vertically spaced, substantially parallel inclined planes.

Accordingly, it will be observed that the plate H I tween the outlet end of one of the U-shaped tubes i4 and the inlet end of an immediately adjoining U-shaped tube. The inlet end of the leg Ma of the unit l0. as well as the discharge end of the leg Nb of the unit l3 are each received in shallow seats 23 formed in the inner face of the tube plate 2|, said legs Ma and hot the tube units l9 and |3 being respectively provided with inlet and outlet connections 24 and 25. The fluid to be heated, which is delivered into the unit ID by way of the inlet connection 24 and is discharged from the unit l3 by way of the outlet connection 25, is circulated through the units H], H, l2 and I3 in the order named, successive pairs of these units being in connection with one another by way of the connecting passages 22 provided in the inner face of the tube plate 2|.

As appears most clearly in Figure 2, the outer face of the tube plate 2| is provided with a U- shaped recess 26 the opposite legs of which are separated from each other by a vertically extending rib 21, the outer face of which lies substantially in the plane of the marginal portion 28 of the tube plate 2|. The rib 21 is in effect a depending continuation of the upper marginal edge of the tube plate 2| with the lower end thereof terminating short of the lower marginal edge of said; plate.

Immediately associated with the tube plate 2| and disposed flatwise against the outer face thereof is a relatively thin diaphragm plate 29, while to the outer side of this diaphragm plate is disposed a cover plate 30 the inner surface of which is provided with a pair of verticallyextending laterally spaced channels 300 and 301) (see Figure 5) connected together by a transversely extending channel 300. The plates I1, 2|, 29 and 39 are securely bolted together by a plurality of marginal bolts 3|, itbeing understood, of course, that if desired suitable gaskets may be interposed between the contacting surfaces of the several plates so clamped together. If desired, and in certain instances it is preferable to do so, the diaphragm plate 29 may be formed of a metal sufilciently soft that when its marginal edge 29a is compressed between the plates 2| and 39 it flows and spreads to form a self-sealing gasket between the said plates 2| and 30. In order to provide adequatespace between the plates 2| and 30 into which the soft metal of the diaphragm plate may be compressed the contacting faces of the plates 2| and 30 are preferably undercut, asat2|a and 30d.

As has already been mentioned, the plate l1 constitutes the support for the outer ends of the laterally spaced legs of the U -shaped tube units IO, M, l2 and L3. The intermediate plates 2| and 29 respectively constitute the tube sheets or plates for the conduits through.which the heating medium is supplied to and through the approject interiorly of each straight-legged portion of the U-shaped tube units IO, N, l2 and I3. There being four of these latter units in the apparatus illustrated in Figure 1, it will be under- I and are substantially coextensive in length with the latter. As appears most clearlyin Figure 3, the outer or rear extremity of each of the tubes 32 is closed, as at 33, while the opposite or inner extremity thereof is open, as at 34, for communication with the U-shaped channel 26 formed in the outer face of the tube plate 2|. The tubes 32 are arranged in laterally spaced pairs so that one set of these tubes is arranged in vertically spaced relation and communicates commonly with one leg of the channel 26 while the other set of these tubes 32 is arranged in similar vertically spaced relation and communicates with the opposite leg of the U-shaped channel 26.

Supported by the diaphragm plate 29 are a plurality of tubes 35 which extend interiorly of and are disposed concentrically within the tubes 33, the tubes 35 being open at both ends thereof, as at 36 and 31, the front ends 31 of these tubes being in communication with the channels .30a-30b provided in the inner face of the cover plate 30. From the foregoing description, it will be seen that the apparatus of the present invention comprises a plurality of U-shaped tube units within each straightleg of which is disposed a pair of concentric tubes, the outer ends of these concentric inner tubes being respectively in communication with passages maintained in separated relation by the diaphragm sheet 29.

As appears most clearly in Figure 1, the outer plate 30 is provided with'an inlet connection 96 while the tube plate 2| is provided at the bottom thereof with an outlet connection 39. While said outlet connection 39 is shown leading directly from the tube plate 2|, it may instead lead outwardly from the bottom of the passage 26 and through the diaphragm and front cover plate 30. In the use of the apparatus as just described, steam employed as the heating medium is introduced to the apparatus by way of the inlet connection 38 while the liquid to be heated, such as oil, is introduced by way of the inlet connection 24, the heat transference from the heating medium to the fluid to be heated being effected by circulating both fluids continuously through the apparatus. The steam which is supplied by way of the inlet 38 enters the steam channels 39a and 30b and is commonly delivered therefrom into the inner'steam tubes 35. into the tubes 36 discharges from therear open ends 36 thereof against the closed ends 33 of the tubes 32 and is returned by the latter through the annular space provided between the concentric tubes as and 32 into the U-shaped channel paratus, which latter conduits will now be de-' 26 formed in the outer face of the tube plate 2|, the steam being finally discharged from the said channel 26 by way of the steam outlet connection 39. The oil to be heated, which is introduced into the apparatus by i'way of the annular spaces formed between the steam when:

and the straight-legged portion of the U-shapect tube units III, II, l2 and I3, the heat of the steam being transferred to the oil through the walls of the steam tubes 32. Due to the fact that the pressure of the steam is substantially equal on either side of the diaphragm plate 29, the latter need not be any stronger than is necessary to The steam so delivered support the inner-steam tubes concentrically withinthetubesfl. Whileanysuitablemeans maybeemployedforsecuringtheseveraltubes of the apparatus in their respective tube plates, itispreferablethatallofthetubmexeeptthe steam injection ll. be expanded into their rapactivetubepla llandil. 'ihesameproceduremaybefollowedasrespectsthe'steaminisetion tubes but those latter are preferably threaded into the diaphragm plate aasshown.

shaped tube units iO-ll of Figure 1,

It is desirable that the diaphragm plate 2. be

provided with an aperture I. adjacent the bottomthereoftoserveasadrainfor'theescape of any condensate which mayaccumulate in thesteam channels Ila-40b of the cover plate. It

will be appreciated, of course, that should any condensate form within the steam tubes 32, such condensate will be driven therefrom by the pressm'eofthesteam dischargingfromtheopen ends I. of the steam injection tubes ll.

Figure '4 illustrates a somewhat modified connecied fiuid conduits in either of the forms of apparatus shown may be varied as desired to suit different installation conditions and space limitations. In the form of apparatus shown in Figure 4, the inner ends of the tubes 4| are suitably expanded into a tube plate 4!. the outer ends of these tubes being closed, as at 0. Communication between the tubes is efiected by means vof connections 44 and ll disposed between successive pairs of the tubes in such manner that a.

continuous supply of oil or other liquid to be heated may be introduced into the apparatus by way of the inlet connection 40 and discharged therefrom by way of the outlet connection 41.

the outer endsofthetubes ll with capslt,provisionishadforthereadyremovai ofthesteamtubestlbywayofsaidcappedends whenever such removalisnecessaryior'cleaning repairs.orinspection.

ltistobeunderstoodthatinplaceoftbeustraight tubes, such as are designated by theerence numeral 4|, may be employed, these latter tubes being capped, as at 43, and connected to- 4. Conversely, the mounting plate assembly for supporting theforward ends of the tubes ll, as in Flames, may be employ d in lieu of v inFigurelforsupportingtheforwa-rde'ndsofthe U-shapedun'its il-II, in which event the connections ll would be employed for eifecfingcommunication between the inlet and outlet points of adjoiningpairs of the units ll-IJ. V

In order to increase the heat conductivity of the steam tubes 83 (Figure 1) or (I (Figure 4) they are preferably provided with longitudinalLv extending circumferentially spaced fins I, these fins being of a depth such that they extend radially from the outer surface of the steam tube to which they are secured into close proximity with the internal surface of the tube through which the oil or other liquid to be heated is circulated. By providing 'the steam tubes with these radially extending fins, the ef-' fective heat transferring surface, of each such tube is very materially increased. While finned tubing'has beenem-ployed priorto the present invention, the type of fin and the manner of securing it to the tube as disclosed herein constis' tutes an important part of the present invention not'only because. of the economies effected thereby in the manufacture of sum/fin tubingbut also because of the increased heat conductivity siforded by the fin tubing oi the present invention. I

Referring now more particularly to Figure 7 p it. will be observed that the radial fins I of the steam tubes '32 (which latter may be the steam tubes 48 of Figure 4) are secured to the outer the liquid being circulated successively through all of the tubes ll of the apparatus.

As in the construction illustrated in Figure 1, in the modified construction the steam tubes 4. are expanded or otherwise secured in a tube plate I! while the steam injection tubes II are screwed or otherwise secured in the diaphragm plate Ii, the latter being clamped between the tube plate II and the cover I! by a plurality of marginal bolts (not shown). The steam tubes 4| are closed attheirrearends,ssatl8,sothatsteamsupplied thereto by the steam injection tubes II is caused to return-by way of the annular space provided between the walls of'the steam tubes ll and the steam injection tubes II to the channel It for ultimate discharge from the apparatus by way of the outlet connection II. In the apparatus oftheconstructicnillustratedinmure4,the severaitubesllaredimosedinasubstantially common vertical planein which the tube plate 4! and the eoverpiate I! may each beprovidedwithsingleverticallydlsposedchannelsllandlhthechannelllservingtodeliver thedischargedsteamsndfromthe surface thereof in the form of a mul is number of pairs-of fins, each pair offins cons tuting the longitudinally extending side walls of a channel having a base 51. The fin-forming channels are secured to the outer surface of the steam tubes by welding the bases thereof to the tubes.

Due to the relatively broad base of the finforming channels, a very ample surface contact is bad between the steam tube and each of said channels in consequence of which a much higherheat conductivity is obtained betweenfthe tube andthefinsthan wouldbethecasewerethefins in edgewise relation to the tube. By

7 means fthefinssecuredtothesteamtubein accordance with the praent invention, the heat .to' efiuid to be heated which-circulates about steam tubes ll to the outlet connection ll while the outer surfaces of said tubes and between the fins thereof.

If desired, in order to insure maintenance ofthe radial finsfl in their proper angular relation, the outer free extremities thereof may be secured together by one or more narrow bands II which extend circumferentially about and embrace the fin extremitiesisee Figures 6 and 'i). Also,inorderto insurethat'thesteaminiection tubes II are at all times supported'coaxially withinithesteamtubes ",thesaid tubes may beprovidedstoneormorelongitudinallyspaced' points with radially projecting arms iii (see Figure 7) which engage the internal walls of the steam tubes 35 and center the steam injection tubes therewithin.

It will be understood, of course,that the invention is susceptible of various changes and modiiications from time to time without departing from the real spirit or general principles thereof and it is accordingly intended to claim the same broadly, as well as specifically, as indicated by the appended claims.

What is claimed as new and useful is:

1. A heat exchanging apparatus-comprising a plurality of interconnected fluid circulating tubes through which a fluid to be heated may be continuously circulated, a plurality of steam tubes respectively projecting longitudinally into said fluid circulating tubes from corresponding open ends of the latter, the inner extremities of said steam tubes being closed while the outer ends thereof are open, and a plurality of steam injection tubes respectively disposed interiorly of said steam tubes, the inner extremities of said steam injection tubes being open and terminating short of the closed extremities of said steam tubes, and means for distributing steam at substantially equal pressure and temperature into said steam tubes by way of said steam injection tubes, said means comprising a diaphragm carrying the steam injection tubes, and a pair of substantially equal plates having flat faces disposed against the opposite faces of said diaphragm clamping the diaphragm over its marginal and intermediate areas, said plates each having on their diaphragm abutting faces a pair of elongated comhaving a steam inlet in communication with said recesses, and the other of said plates having the open ends of said steam tubes mounted therein in communication with said recesses and also having a steam outlet communicating with its recesses. 7

2. In a heat exchanging apparatus, a plurality of interconnected fluid circulating conduits having substantially straight portions arranged in parallel relation, a plurality of steam tubes having closed rear ends respectively disposed interiorly of the straight portions of said conduits, means interconnecting adjoining pairs of said conduits adjacent the extremities thereof whereby said conduits are connected in series relation, the fluid to be heated being circulated in said series connected conduits continuously through the space provided between the concentric walls of said conduits and tubes, a mounting plate serving commonly as a support for the outer open ends of said tubes. and as a closure for the outer extremities of said conduits, a plurality of steam injection tubes respectively disposed interiorly of said above-mentioned heating tubes and adapted to deliver a heating medium against the closed rear ends of the latter for subsequent discharge therefrom through the space provided between the concentric walls of said tubes, and means for distributing said heating medium commonly into said delivery tubes from a source of supply of said heating medium, said means comprising a diaphragm carrying the steam injection tubes, and a pair of substantially equal plates having flat faces disposed against the opposite faces of said diaphragm clamping the diaphragm over its marginal and intermediate areas, said plates each having on their diaphragm abutting faces a pair of elongated communicating shallow recesses, one of said plates having a steam inlet in communication with said recesses, and the other of said plates having the open ends of said steam tubes mounted therein in communication with said recesses and also having a steam outlet communithe same in spaced relation, a plurality of tubes municating shallow recesses, one of said plates projecting interiorly of said conduits through the outer ends thereof, a mounting plate for said tubes disposed in flatwise engagement with said conduit mounting plate, said tube mounting plate being provided in its inner face with passages afiording communication between adjoining pairs of said conduits and with passages in its outer face affording communication between the outer extremities of said tubes, and means for injecting a heating medium interiorly of said tubes for heating the walls thereof, said heating medium being discharged from said tubes through the forward ends thereof and by way of said passages provided in the outer face of the tube mounting plate, said last-mentioned means including a plurality of relatively small diameter tubes disposed concentrically within said heating tubes to provide an annular space between the walls of said concentric tubes through which the heating medium flows upon its discharge from the inner ends of said small diameter tubes, a diaphragm carrying said small diameter tubes and having a face disposed flat against the outer face of said tube mounting plate, an outer plate disposed flat against the other face of said diaphragm and having a pair of shallow elongated communicating recesses in registry with said small diameter tubes, and a heating fluid inlet in communication with said last named recesses.

' JAMES P. ZALLEA. 

